P1 + H3-2D + GoPro Hero 3...advice needed please

We have a P1 which came with an H3-2D gimbal. We've added a Fatshark video TX. I am thinking about buying a GP Hero 3 but need to know if we need anything else apart from a cable to connect the camera to the video TX.

I've opened the P1 up and the black cable from the gimbal connects directly to the main PCB. There are no other modules or interfaces. My confusion has been that on the DJI website the manual for the gimbal suggests you need interface module(s) in order for it to work. Is that correct?